Patent GB-789905-A (GB)
Title: Reclamation of components of complex esters from lubricating oils
IPC: C07C43/11
Filed: 1955-09-28
Abstract: Components of a complex ester of formula A-(Glycol-Dibasic acid)x-B, in which A is a monobasic acid residue or a monohydric alcoholdibasic acid residue, B is a monohydric alcohol residue or a monobasic acid-glycol residue and x is an integer of 1 to 6, are recovered from a lubricating oil composition by forming a mixture comprising the lubricating oil composition, containing at least 1 per cent by volume of the complex ester, a monohydric alcohol and an esterification catalyst, heating the mixture until a part of the complex ester is transesterified into a free glycol product and a diester product of the dibasic acid, and separating the products from the mixture. Alcohols which may be used in the preparation of the complex esters are amyl, 2-ethylbutyl, n-hexyl, n-octyl, 2-ethylhexyl, nonyl, decyl and C7, C8, C9, C10 and C13 oxo alcohols as well as ether alcohols formed by the reaction of ethylene oxide or propylene oxide with aliphatic alcohols.  The monobasic acid components are preferably from acids having 4-13 carbon atoms. Suitable acids are propionic, butyric, 2-ethylbutyric, valeric, caproic, 2-ethylhexoic and caprylic acids, C8, C10 and C13 oxo acids, lauric acid and the corresponding thio acids.  The dibasic acid components may be, for example, succinic, adipic, pimelic, suberic, azelaic, sebacic, isosebacic, trimethyladipic and a -methyladipic acids.  The glycols may be ethylene glycol and its homologues, polyethylene glycols, polypropylene glycols and also thioglycols.  The oil compositions from which the glycol and dibasic acid complex ester components are to be recovered may contain other materials such as mineral lubricating oil base stocks, water, kerosine, naphtha, light gas oils and diesters as well as various conventional additives.  The alcohol used in the transesterification reaction may be the same as that used originally in the preparation of the complex ester or of the diester base stock.  It is desirable to use at least 2 mols. of monohydric alcohol per dibasic acid unit in addition to one mol. for each monobasic acid unit in each mol. of the complex ester.  Suitable esterification catalysts are, for example, sulphuric acid, sodium hydrogen sulphate, p-toluene sulphonic acid and sulphosalicylic acid. The reaction is carried out preferably in a temperature in the range 150 DEG  to 250 DEG  C.  In the example a used synthetic lubricating oil containing 2 - ethylhexanol - sebacic acid - (tetraethylene glycol-sebacic acid)-2-ethylhexanol is mixed with 2-ethyl hexanol and sodium bisulphate as catalyst and the mixture is refluxed; tetraethylene glycol and di-2-ethylhexyl sebacate are separated from the product.ALSO:Components of the complex ester present are reclaimed from a used synthetic lubricating oil composition consisting originally of 1 per cent (by weight) of phenothiazine and 99 per cent of a synthetic oil base stock prepared by blending 25 per cent (by volume) of di-2-ethyl-hexyl sebacate with 75 per cent of a complex ester having the approximate formula 2 - ethylhexanol - sebacic acid - (tetraethylene glycol - sebacic acid) - 2 - ethyl - hexanol.